The effects of i.p. administration of the γ-aminobutyric acid (GABA) uptake inhibitors R(−)N-(4,4-di(3-methylthien-2-yl)-but-3-enyl) nipecotic acid hydrochloride (tiagabine; molecular weight 412.0), (1-(2-(((diphenylmethylene)-amino)oxy)ethyl)-1,2,5,6-tetrahydro-3-pyridinecarboxylic acid hydrochloride (NNC-711; molecular weight 386.9), and (±)-nipecotic acid (molecular weight 128.2) are compared with those of carbamazepine (molecular weight 236.3) on sound-induced seizures and locomotor performance in genetically epilepsy-prone (GEP) rats. The ED 50 value against clonic seizures (in μmol kg −1 at the time of maximal anticonvulsant effect) for tiagabine was 23 (0.5 h), and for NNC-711 was 72 (1 h), and for carbamazepine was 98 (2 h). (±)-Nipecotic acid (0.4–15.6) mmol kg −1 ) was not anticonvulsant. High doses of NNC-711 (207–310 μmol kg −1 ) and of (±)-nipecotic acid (39–78 mmol kg −1 ) induced ataxia and myoclonic seizures 0.25–1 h. Tiagabine and carbamazepine did not induce myoclonic seizures and had similar therapeutic indices (locomotor deficit ED 50 /anticonvulsant ED 50 ) ranging from 0.4 to 1.9. In Papio papio, we observed a reduction in photically induced myoclonic seizures with tiagabine (2.4 μmol kg −1 i.v.) accompanied with neurological impairment. Tiagabine has comparable anticonvulsant action to carbamazepine in rats and has anticonvulsant effects in non-human primates supporting the potential use of inhibitors of GABA uptake as therapy for epilepsy.